The invention relates to a device for the detection of electromagnetic waves, especially waves of the infrared spectrum, and a method for producing such a device.
Miniature devices for the detection of electromagnetic waves are used for a multitude of purposes. Particularly in medical devices, like for example a so called “ear thermometer”, devices for the detection of electromagnetic waves in the infrared spectrum are already broadly used today. Home climate control, home safety and alarm systems, automotive applications, such as in-door climate control, replacement of pyrometers and many other industrial applications offer multiple future uses for such devices.
In the field of infrared sensors, DE 199 23 606 A1 describes a device for the detection of electromagnetic waves that contains a lower mounting plate, on which a substrate with a detector structure is built. A top plate is attached to the lower mounting plate while distance maintaining support structures keep a distance between the top and the lower plate. The top plate has a lens that is produced on the top plate by means of micro mechanics. The lower plate has a cavity that opens towards its lower (rear) end and terminates at a thin membrane at its top (front) end on which the detector structure is built.
In a further embodiment, DE 199 23 606 A1 teaches the detector structure to be affixed to a thin membrane, which thin membrane is then affixed to the (only) top plate.
DE 199 23 606 A1 discloses the lower plate and the support structures to be built on the wafer level as well as the top plate to be manufactured as part of a wafer. According to DE 199 23 606 A1, the two wafers are aligned and connected to each other, after which the respective sensors are produced by separation.
The devices disclosed in DE 199 23 606 A1 are considered to measure inaccurately and to require costly production methods. Furthermore connecting the detection structure of the disclosed devices to subsequent electronic evaluation devices is either space consuming or difficult to achieve.
From DE 41 02 524 A1 an infrared sensor is known with a detector structure being fixed to the front side of a semi conductor substrate (thermistor). This thermistor is attached to a lower plate with its backside. Connections for the detector structure are led through the lower plate. At the topside of the lower plate (to which the thermistor is also attached) free standing wires connect the connections in the second plate to connectors on the detector structure and the thermistor.
The lower plate carrying the thermistor is covered by a cup-shaped cover that is affixed to the sidewalls of the lower plate.
The device known from DE 41 02 524 A1 is disadvantageous, because it is difficult and costly to produce.